Handling single uplink transmissions in a dual connectivity mode

ABSTRACT

Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a user equipment (UE) may determine whether an uplink communication for a first radio access technology (RAT) has been dynamically scheduled or semi-statically configured, wherein the UE is in a dual connectivity mode using the first RAT and a second RAT. The UE may identify an uplink subframe for transmission of the uplink communication based at least in part on whether the uplink communication has been dynamically scheduled or semi-statically configured, and based at least in part on a downlink-reference uplink-downlink configuration. The UE may transmit the uplink communication in the identified uplink subframe. Numerous other aspects are provided.

CROSS-REFERENCE TO RELATED APPLICATION

This Patent Application claims priority to U.S. Provisional PatentApplication No. 62/885,008, filed on Aug. 9, 2019, entitled “HANDLINGSINGLE UPLINK TRANSMISSIONS IN A DUAL CONNECTIVITY MODE,” and assignedto the assignee hereof. The disclosure of the prior Application isconsidered part of and is incorporated by reference in this PatentApplication.

FIELD OF THE DISCLOSURE

Aspects of the present disclosure generally relate to wirelesscommunication and to techniques and apparatuses for handling singleuplink transmissions in a dual connectivity mode.

BACKGROUND

Wireless communication systems are widely deployed to provide varioustelecommunication services such as telephony, video, data, messaging,and broadcasts. Typical wireless communication systems may employmultiple-access technologies capable of supporting communication withmultiple users by sharing available system resources (e.g., bandwidth,transmit power, etc.). Examples of such multiple-access technologiesinclude code division multiple access (CDMA) systems, time divisionmultiple access (TDMA) systems, frequency-division multiple access(FDMA) systems, orthogonal frequency-division multiple access (OFDMA)systems, single-carrier frequency-division multiple access (SC-FDMA)systems, time division synchronous code division multiple access(TD-SCDMA) systems, and Long Term Evolution (LTE). LTE/LTE-Advanced is aset of enhancements to the Universal Mobile Telecommunications System(UMTS) mobile standard promulgated by the Third Generation PartnershipProject (3GPP).

A wireless communication network may include a number of base stations(BSs) that can support communication for a number of user equipment(UEs). A user equipment (UE) may communicate with a base station (BS)via the downlink and uplink. The downlink (or forward link) refers tothe communication link from the BS to the UE, and the uplink (or reverselink) refers to the communication link from the UE to the BS. As will bedescribed in more detail herein, a BS may be referred to as a Node B, agNB, an access point (AP), a radio head, a transmit receive point (TRP),a new radio (NR) BS, a 5G Node B, and/or the like.

The above multiple access technologies have been adopted in varioustelecommunication standards to provide a common protocol that enablesdifferent user equipment to communicate on a municipal, national,regional, and even global level. New radio (NR), which may also bereferred to as 5G, is a set of enhancements to the LTE mobile standardpromulgated by the Third Generation Partnership Project (3GPP). NR isdesigned to better support mobile broadband Internet access by improvingspectral efficiency, lowering costs, improving services, making use ofnew spectrum, and better integrating with other open standards usingorthogonal frequency division multiplexing (OFDM) with a cyclic prefix(CP) (CP-OFDM) on the downlink (DL), using CP-OFDM and/or SC-FDM (e.g.,also known as discrete Fourier transform spread OFDM (DFT-s-OFDM)) onthe uplink (UL), as well as supporting beamforming, multiple-inputmultiple-output (MIMO) antenna technology, and carrier aggregation.

SUMMARY

In some aspects, a method of wireless communication, performed by a userequipment (UE), may include determining whether an uplink communicationfor a first radio access technology (RAT) has been dynamically scheduledor semi-statically configured, wherein the UE is in a dual connectivitymode using the first RAT and a second RAT; identifying an uplinksubframe for transmission of the uplink communication based at least inpart on whether the uplink communication has been dynamically scheduledor semi-statically configured and based at least in part on adownlink-reference uplink-downlink configuration; and transmitting theuplink communication in the identified uplink subframe.

In some aspects, a method of wireless communication, performed by a UE,may include determining a type of an uplink communication for a firstRAT, wherein the UE is in a dual connectivity mode using the first RATand a second RAT; identifying a subframe for transmission of the uplinkcommunication based at least in part on the type of the uplinkcommunication and based at least in part on a downlink-referenceuplink-downlink configuration; and transmitting the uplink communicationin the identified subframe.

In some aspects, a method of wireless communication, performed by a UE,may include identifying one or more symbols, in an uplink subframedesignated as uplink by a downlink-reference uplink-downlinkconfiguration, in which the UE is not permitted to transmit an uplinkcommunication for a first RAT, wherein the UE is in a dual connectivitymode using the first RAT and a second RAT; and transmitting an uplinkcommunication for the second RAT in the identified one or more symbols.

In some aspects, a UE for wireless communication may include memory andone or more processors operatively coupled to the memory. The memory andthe one or more processors may be configured to determine whether anuplink communication for a first RAT has been dynamically scheduled orsemi-statically configured, wherein the UE is in a dual connectivitymode using the first RAT and a second RAT; identify an uplink subframefor transmission of the uplink communication based at least in part onwhether the uplink communication has been dynamically scheduled orsemi-statically configured and based at least in part on adownlink-reference uplink-downlink configuration; and transmit theuplink communication in the identified uplink subframe.

In some aspects, a UE for wireless communication may include memory andone or more processors operatively coupled to the memory. The memory andthe one or more processors may be configured to determine a type of anuplink communication for a first RAT, wherein the UE is in a dualconnectivity mode using the first RAT and a second RAT; identify asubframe for transmission of the uplink communication based at least inpart on the type of the uplink communication and based at least in parton a downlink-reference uplink-downlink configuration; and transmit theuplink communication in the identified subframe.

In some aspects, a UE for wireless communication may include memory andone or more processors operatively coupled to the memory. The memory andthe one or more processors may be configured to identify one or moresymbols, in an uplink subframe designated as uplink by adownlink-reference uplink-downlink configuration, in which the UE is notpermitted to transmit an uplink communication for a first RAT, whereinthe UE is in a dual connectivity mode using the first RAT and a secondRAT; and transmit an uplink communication for the second RAT in theidentified one or more symbols.

In some aspects, a non-transitory computer-readable medium may store oneor more instructions for wireless communication. The one or moreinstructions, when executed by one or more processors of a UE, may causethe one or more processors to: determine whether an uplink communicationfor a first RAT has been dynamically scheduled or semi-staticallyconfigured, wherein the UE is in a dual connectivity mode using thefirst RAT and a second RAT; identify an uplink subframe for transmissionof the uplink communication based at least in part on whether the uplinkcommunication has been dynamically scheduled or semi-staticallyconfigured and based at least in part on a downlink-referenceuplink-downlink configuration; and transmit the uplink communication inthe identified uplink subframe.

In some aspects, a non-transitory computer-readable medium may store oneor more instructions for wireless communication. The one or moreinstructions, when executed by one or more processors of a UE, may causethe one or more processors to: determine a type of an uplinkcommunication for a first RAT, wherein the UE is in a dual connectivitymode using the first RAT and a second RAT; identify a subframe fortransmission of the uplink communication based at least in part on thetype of the uplink communication and based at least in part on adownlink-reference uplink-downlink configuration; and transmit theuplink communication in the identified subframe.

In some aspects, a non-transitory computer-readable medium may store oneor more instructions for wireless communication. The one or moreinstructions, when executed by one or more processors of a UE, may causethe one or more processors to: identify one or more symbols, in anuplink subframe designated as uplink by a downlink-referenceuplink-downlink configuration, in which the UE is not permitted totransmit an uplink communication for a first RAT, wherein the UE is in adual connectivity mode using the first RAT and a second RAT; andtransmit an uplink communication for the second RAT in the identifiedone or more symbols.

In some aspects, an apparatus for wireless communication may includemeans for determining whether an uplink communication for a first RAThas been dynamically scheduled or semi-statically configured, whereinthe apparatus is in a dual connectivity mode using the first RAT and asecond RAT; means for identifying an uplink subframe for transmission ofthe uplink communication based at least in part on whether the uplinkcommunication has been dynamically scheduled or semi-staticallyconfigured and based at least in part on a downlink-referenceuplink-downlink configuration; and means for transmitting the uplinkcommunication in the identified uplink subframe.

In some aspects, an apparatus for wireless communication may includemeans for determining a type of an uplink communication for a first RAT,wherein the apparatus is in a dual connectivity mode using the first RATand a second RAT; means for identifying a subframe for transmission ofthe uplink communication based at least in part on the type of theuplink communication and based at least in part on a downlink-referenceuplink-downlink configuration; and means for transmitting the uplinkcommunication in the identified subframe.

In some aspects, an apparatus for wireless communication may includemeans for identifying one or more symbols, in an uplink subframedesignated as uplink by a downlink-reference uplink-downlinkconfiguration, in which the apparatus is not permitted to transmit anuplink communication for a first RAT, wherein the apparatus is in a dualconnectivity mode using the first RAT and a second RAT; and means fortransmitting an uplink communication for the second RAT in theidentified one or more symbols.

Aspects generally include a method, apparatus, system, computer programproduct, non-transitory computer-readable medium, user equipment, basestation, wireless communication device, and/or processing system assubstantially described with reference to and as illustrated by theaccompanying drawings and specification.

The foregoing has outlined rather broadly the features and technicaladvantages of examples according to the disclosure in order that thedetailed description that follows may be better understood. Additionalfeatures and advantages will be described hereinafter. The conceptionand specific examples disclosed may be readily utilized as a basis formodifying or designing other structures for carrying out the samepurposes of the present disclosure. Such equivalent constructions do notdepart from the scope of the appended claims. Characteristics of theconcepts disclosed herein, both their organization and method ofoperation, together with associated advantages will be better understoodfrom the following description when considered in connection with theaccompanying figures. Each of the figures is provided for the purposesof illustration and description, and not as a definition of the limitsof the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the above-recited features of the present disclosure can beunderstood in detail, a more particular description, briefly summarizedabove, may be had by reference to aspects, some of which are illustratedin the appended drawings. It is to be noted, however, that the appendeddrawings illustrate only certain typical aspects of this disclosure andare therefore not to be considered limiting of its scope, for thedescription may admit to other equally effective aspects. The samereference numbers in different drawings may identify the same or similarelements.

FIG. 1 is a diagram illustrating an example of a wireless communicationnetwork, in accordance with various aspects of the present disclosure.

FIG. 2 is a diagram illustrating an example of a base station incommunication with a UE in a wireless communication network, inaccordance with various aspects of the present disclosure.

FIG. 3 is a diagram illustrating an example of behavior of a type 1 UEfor handling single uplink transmissions in a dual connectivity mode.

FIG. 4 is a diagram illustrating an example of behavior of a type 2 UEfor handling single uplink transmissions in a dual connectivity mode.

FIGS. 5-9 are diagrams illustrating examples of handling single uplinktransmissions in a dual connectivity mode, in accordance with variousaspects of the present disclosure.

FIGS. 10-12 are diagrams illustrating example processes performed, forexample, by a user equipment, in accordance with various aspects of thepresent disclosure.

DETAILED DESCRIPTION

For a type 1 UE operating in a single uplink transmission mode and anEvolved Universal Terrestrial Radio Access (EUTRA) New Radio (NR) DualConnectivity (ENDC or EN-DC) mode and configured with a time-divisionduplex (TDD) primary cell (PCell), if there is a collision between anLTE physical uplink shared channel (PUSCH) communication and an NR PUSCHcommunication, then the UE may drop the NR PUSCH communication and maytransmit the LTE PUSCH communication. By dropping NR PUSCHcommunications in favor of LTE PUSCH communications in uplink subframesdesignated as uplink by a downlink (DL)-reference uplink-downlink(UL/DL) configuration, the UE may avoid a collision. However, some otherLTE uplink communications may be handled differently. If such LTE uplinkcommunications are permitted on all UL subframes of an LTE TDD UL/DLconfiguration (e.g., regardless of whether those UL subframes aredesignated as UL by the DL-reference UL/DL configuration), then theopportunities for NR uplink communications may be highly limited due tothe number of such LTE UL communications, thereby degrading NRperformance. However, if such LTE UL communications are limited to ULsubframes designated as UL by the DL-reference UL/DL configuration, thenthe opportunity for transmission of such LTE UL communications may belimited, which may degrade performance of LTE communications and causeinterference and congestion on the UL subframes designated as UL by theDL-reference UL/DL configuration. Some techniques and apparatusesdescribed herein address these and other issues, and permit flexible andefficient transmission of uplink communications for a UE operating in asingle transmission mode in ENDC with a TDD PCell.

Various aspects of the disclosure are described more fully hereinafterwith reference to the accompanying drawings. This disclosure may,however, be embodied in many different forms and should not be construedas limited to any specific structure or function presented throughoutthis disclosure. Rather, these aspects are provided so that thisdisclosure will be thorough and complete, and will fully convey thescope of the disclosure to those skilled in the art. Based on theteachings herein one skilled in the art should appreciate that the scopeof the disclosure is intended to cover any aspect of the disclosuredisclosed herein, whether implemented independently of or combined withany other aspect of the disclosure. For example, an apparatus may beimplemented or a method may be practiced using any number of the aspectsset forth herein. In addition, the scope of the disclosure is intendedto cover such an apparatus or method which is practiced using otherstructure, functionality, or structure and functionality in addition toor other than the various aspects of the disclosure set forth herein. Itshould be understood that any aspect of the disclosure disclosed hereinmay be embodied by one or more elements of a claim.

Several aspects of telecommunication systems will now be presented withreference to various apparatuses and techniques. These apparatuses andtechniques will be described in the following detailed description andillustrated in the accompanying drawings by various blocks, modules,components, circuits, steps, processes, algorithms, etc. (collectivelyreferred to as “elements”). These elements may be implemented usinghardware, software, or combinations thereof. Whether such elements areimplemented as hardware or software depends upon the particularapplication and design constraints imposed on the overall system.

It should be noted that while aspects may be described herein usingterminology commonly associated with 3G and/or 4G wireless technologies,aspects of the present disclosure can be applied in othergeneration-based communication systems, such as 5G and later, includingNR technologies.

FIG. 1 is a diagram illustrating a wireless network 100 in which aspectsof the present disclosure may be practiced. The wireless network 100 maybe an LTE network or some other wireless network, such as a 5G or NRnetwork. The wireless network 100 may include a number of BSs 110 (shownas BS 110 a, BS 110 b, BS 110 c, and BS 110 d) and other networkentities. ABS is an entity that communicates with user equipment (UEs)and may also be referred to as a base station, a NR BS, a Node B, a gNB,a 5G node B (NB), an access point, a transmit receive point (TRP),and/or the like. Each BS may provide communication coverage for aparticular geographic area. In 3GPP, the term “cell” can refer to acoverage area of a BS and/or a BS subsystem serving this coverage area,depending on the context in which the term is used.

A BS may provide communication coverage for a macro cell, a pico cell, afemto cell, and/or another type of cell. A macro cell may cover arelatively large geographic area (e.g., several kilometers in radius)and may allow unrestricted access by UEs with service subscription. Apico cell may cover a relatively small geographic area and may allowunrestricted access by UEs with service subscription. A femto cell maycover a relatively small geographic area (e.g., a home) and may allowrestricted access by UEs having association with the femto cell (e.g.,UEs in a closed subscriber group (CSG)). ABS for a macro cell may bereferred to as a macro BS. ABS for a pico cell may be referred to as apico BS. A BS for a femto cell may be referred to as a femto BS or ahome BS. In the example shown in FIG. 1, a BS 110 a may be a macro BSfor a macro cell 102 a, a BS 110 b may be a pico BS for a pico cell 102b, and a BS 110 c may be a femto BS for a femto cell 102 c. A BS maysupport one or multiple (e.g., three) cells. The terms “eNB”, “basestation”, “NR BS”, “gNB”, “TRP”, “AP”, “node B”, “5G NB”, and “cell” maybe used interchangeably herein.

In some examples, a cell may not necessarily be stationary, and thegeographic area of the cell may move according to the location of amobile BS. In some examples, the BSs may be interconnected to oneanother and/or to one or more other BSs or network nodes (not shown) inthe wireless network 100 through various types of backhaul interfacessuch as a direct physical connection, a virtual network, and/or the likeusing any suitable transport network.

Wireless network 100 may also include relay stations. A relay station isan entity that can receive a transmission of data from an upstreamstation (e.g., a BS or a UE) and send a transmission of the data to adownstream station (e.g., a UE or a BS). A relay station may also be aUE that can relay transmissions for other UEs. In the example shown inFIG. 1, a relay station 110 d may communicate with macro BS 110 a and aUE 120 d in order to facilitate communication between BS 110 a and UE120 d. A relay station may also be referred to as a relay BS, a relaybase station, a relay, etc.

Wireless network 100 may be a heterogeneous network that includes BSs ofdifferent types, e.g., macro BSs, pico BSs, femto BSs, relay BSs, etc.These different types of BSs may have different transmit power levels,different coverage areas, and different impacts on interference inwireless network 100. For example, macro BSs may have a high transmitpower level (e.g., 5 to 40 watts) whereas pico BSs, femto BSs, and relayBSs may have lower transmit power levels (e.g., 0.1 to 2 watts).

A network controller 130 may couple to a set of BSs and may providecoordination and control for these BSs. Network controller 130 maycommunicate with the BSs via a backhaul. The BSs may also communicatewith one another, e.g., directly or indirectly via a wireless orwireline backhaul.

UEs 120 (e.g., 120 a, 120 b, 120 c) may be dispersed throughout wirelessnetwork 100, and each UE may be stationary or mobile. A UE may also bereferred to as an access terminal, a terminal, a mobile station, asubscriber unit, a station, etc. A UE may be a cellular phone (e.g., asmart phone), a personal digital assistant (PDA), a wireless modem, awireless communication device, a handheld device, a laptop computer, acordless phone, a wireless local loop (WLL) station, a tablet, a camera,a gaming device, a netbook, a smartbook, an ultrabook, a medical deviceor equipment, biometric sensors/devices, wearable devices (smartwatches, smart clothing, smart glasses, smart wrist bands, smart jewelry(e.g., smart ring, smart bracelet)), an entertainment device (e.g., amusic or video device, or a satellite radio), a vehicular component orsensor, smart meters/sensors, industrial manufacturing equipment, aglobal positioning system device, or any other suitable device that isconfigured to communicate via a wireless or wired medium.

Some UEs may be considered machine-type communication (MTC) or evolvedor enhanced machine-type communication (eMTC) UEs. MTC and eMTC UEsinclude, for example, robots, drones, remote devices, sensors, meters,monitors, location tags, etc., that may communicate with a base station,another device (e.g., remote device), or some other entity. A wirelessnode may provide, for example, connectivity for or to a network (e.g., awide area network such as Internet or a cellular network) via a wired orwireless communication link. Some UEs may be consideredInternet-of-Things (IoT) devices, and/or may be implemented as may beimplemented as NB-IoT (narrowband internet of things) devices. Some UEsmay be considered a Customer Premises Equipment (CPE). UE 120 may beincluded inside a housing that houses components of UE 120, such asprocessor components, memory components, and/or the like.

In general, any number of wireless networks may be deployed in a givengeographic area. Each wireless network may support a particular RAT andmay operate on one or more frequencies. A RAT may also be referred to asa radio technology, an air interface, etc. A frequency may also bereferred to as a carrier, a frequency channel, etc. Each frequency maysupport a single RAT in a given geographic area in order to avoidinterference between wireless networks of different RATs. In some cases,NR or 5G RAT networks may be deployed.

In some examples, access to the air interface may be scheduled, whereina scheduling entity (e.g., a base station) allocates resources forcommunication among some or all devices and equipment within thescheduling entity's service area or cell. Within the present disclosure,as discussed further below, the scheduling entity may be responsible forscheduling, assigning, reconfiguring, and releasing resources for one ormore subordinate entities. That is, for scheduled communication,subordinate entities utilize resources allocated by the schedulingentity.

Base stations are not the only entities that may function as ascheduling entity. That is, in some examples, a UE may function as ascheduling entity, scheduling resources for one or more subordinateentities (e.g., one or more other UEs). In this example, the UE isfunctioning as a scheduling entity, and other UEs utilize resourcesscheduled by the UE for wireless communication. A UE may function as ascheduling entity in a peer-to-peer (P2P) network, and/or in a meshnetwork. In a mesh network example, UEs may optionally communicatedirectly with one another in addition to communicating with thescheduling entity.

Thus, in a wireless communication network with a scheduled access totime-frequency resources and having a cellular configuration, a P2Pconfiguration, and a mesh configuration, a scheduling entity and one ormore subordinate entities may communicate utilizing the scheduledresources.

In some aspects, two or more UEs 120 (e.g., shown as UE 120 a and UE 120e) may communicate directly using one or more sidelink channels (e.g.,without using a base station 110 as an intermediary to communicate withone another). For example, the UEs 120 may communicate usingpeer-to-peer (P2P) communications, device-to-device (D2D)communications, a vehicle-to-everything (V2X) protocol (e.g., which mayinclude a vehicle-to-vehicle (V2V) protocol, a vehicle-to-infrastructure(V2I) protocol, and/or the like), a mesh network, and/or the like. Inthis case, the UE 120 may perform scheduling operations, resourceselection operations, and/or other operations described elsewhere hereinas being performed by the base station 110.

As indicated above, FIG. 1 is provided merely as an example. Otherexamples may differ from what is described with regard to FIG. 1.

FIG. 2 shows a block diagram of a design 200 of base station 110 and UE120, which may be one of the base stations and one of the UEs in FIG. 1.Base station 110 may be equipped with T antennas 234 a through 234 t,and UE 120 may be equipped with R antennas 252 a through 252 r, where ingeneral T>1 and R>1.

At base station 110, a transmit processor 220 may receive data from adata source 212 for one or more UEs, select one or more modulation andcoding schemes (MCS) for each UE based at least in part on channelquality indicators (CQIs) received from the UE, process (e.g., encodeand modulate) the data for each UE based at least in part on the MCS(s)selected for the UE, and provide data symbols for all UEs. Transmitprocessor 220 may also process system information (e.g., for semi-staticresource partitioning information (SRPI), etc.) and control information(e.g., CQI requests, grants, upper layer signaling, etc.) and provideoverhead symbols and control symbols. Transmit processor 220 may alsogenerate reference symbols for reference signals (e.g., thecell-specific reference signal (CRS)) and synchronization signals (e.g.,the primary synchronization signal (PSS) and secondary synchronizationsignal (SSS)). A transmit (TX) multiple-input multiple-output (MIMO)processor 230 may perform spatial processing (e.g., precoding) on thedata symbols, the control symbols, the overhead symbols, and/or thereference symbols, if applicable, and may provide T output symbolstreams to T modulators (MODs) 232 a through 232 t. Each modulator 232may process a respective output symbol stream (e.g., for OFDM, etc.) toobtain an output sample stream. Each modulator 232 may further process(e.g., convert to analog, amplify, filter, and upconvert) the outputsample stream to obtain a downlink signal. T downlink signals frommodulators 232 a through 232 t may be transmitted via T antennas 234 athrough 234 t, respectively. According to various aspects described inmore detail below, the synchronization signals can be generated withlocation encoding to convey additional information.

At UE 120, antennas 252 a through 252 r may receive the downlink signalsfrom base station 110 and/or other base stations and may providereceived signals to demodulators (DEMODs) 254 a through 254 r,respectively. Each demodulator 254 may condition (e.g., filter, amplify,downconvert, and digitize) a received signal to obtain input samples.Each demodulator 254 may further process the input samples (e.g., forOFDM, etc.) to obtain received symbols. A MIMO detector 256 may obtainreceived symbols from all R demodulators 254 a through 254 r, performMIMO detection on the received symbols if applicable, and providedetected symbols. A receive processor 258 may process (e.g., demodulateand decode) the detected symbols, provide decoded data for UE 120 to adata sink 260, and provide decoded control information and systeminformation to a controller/processor 280. A channel processor maydetermine reference signal received power (RSRP), received signalstrength indicator (RSSI), reference signal received quality (RSRQ),channel quality indicator (CQI), etc. In some aspects, one or morecomponents of UE 120 may be included in a housing.

On the uplink, at UE 120, a transmit processor 264 may receive andprocess data from a data source 262 and control information (e.g., forreports comprising RSRP, RSSI, RSRQ, CQI, etc.) fromcontroller/processor 280. Transmit processor 264 may also generatereference symbols for one or more reference signals. The symbols fromtransmit processor 264 may be precoded by a TX MIMO processor 266 ifapplicable, further processed by modulators 254 a through 254 r (e.g.,for DFT-s-OFDM, CP-OFDM, etc.), and transmitted to base station 110. Atbase station 110, the uplink signals from UE 120 and other UEs may bereceived by antennas 234, processed by demodulators 232, detected by aMIMO detector 236 if applicable, and further processed by a receiveprocessor 238 to obtain decoded data and control information sent by UE120. Receive processor 238 may provide the decoded data to a data sink239 and the decoded control information to controller/processor 240.Base station 110 may include communication unit 244 and communicate tonetwork controller 130 via communication unit 244. Network controller130 may include communication unit 294, controller/processor 290, andmemory 292.

Controller/processor 240 of base station 110, controller/processor 280of UE 120, and/or any other component(s) of FIG. 2 may perform one ormore techniques associated with handling single uplink transmissions ina dual connectivity mode, as described in more detail elsewhere herein.For example, controller/processor 240 of base station 110,controller/processor 280 of UE 120, and/or any other component(s) ofFIG. 2 may perform or direct operations of, for example, process 1000 ofFIG. 10, process 1100 of FIG. 11, process 1200 of FIG. 12, and/or otherprocesses as described herein. Memories 242 and 282 may store data andprogram codes for base station 110 and UE 120, respectively. The storedprogram codes, when executed by processor 280 and/or other processorsand modules at UE 120, may cause the UE 120 to perform operationsdescribed with respect to process 1000 of FIG. 10, process 1100 of FIG.11, process 1200 of FIG. 12, and/or other processes as described herein.A scheduler 246 may schedule UEs for data transmission on the downlinkand/or uplink.

In some aspects, UE 120 may include means for determining whether anuplink communication for a first RAT has been dynamically scheduled orsemi-statically configured, wherein the UE 120 is in a dual connectivitymode using the first RAT and a second RAT; means for identifying anuplink subframe for transmission of the uplink communication based atleast in part on whether the uplink communication has been dynamicallyscheduled or semi-statically configured and based at least in part on adownlink-reference uplink-downlink configuration; means for transmittingthe uplink communication in the identified uplink subframe; and/or thelike. Additionally, or alternatively, UE 120 may include means fordetermining a type of an uplink communication for a first RAT, whereinthe UE 120 is in a dual connectivity mode using the first RAT and asecond RAT; means for identifying a subframe for transmission of theuplink communication based at least in part on the type of the uplinkcommunication and based at least in part on a downlink-referenceuplink-downlink configuration; means for transmitting the uplinkcommunication in the identified subframe; and/or the like. Additionally,or alternatively, UE 120 may include means for identifying one or moresymbols, in an uplink subframe designated as uplink by adownlink-reference uplink-downlink configuration, in which the UE 120 isnot permitted to transmit an uplink communication for a first RAT,wherein the UE 120 is in a dual connectivity mode using the first RATand a second RAT; means for transmitting an uplink communication for thesecond RAT in the identified one or more symbols; and/or the like. Insome aspects, such means may include one or more components of UE 120described in connection with FIG. 2.

While blocks in FIG. 2 are illustrated as distinct components, thefunctions described above with respect to the blocks may be implementedin a single hardware, software, or combination component or in variouscombinations of components. For example, the functions described withrespect to the transmit processor 264, the receive processor 258, and/orthe TX MIMO processor 266 may be performed by or under the control ofprocessor 280.

As indicated above, FIG. 2 is provided merely as an example. Otherexamples may differ from what is described with regard to FIG. 2.

FIG. 3 is a diagram illustrating an example 300 of behavior of a type 1UE (e.g., a UE with a dynamic power sharing capability) for handlingsingle uplink transmissions in a dual connectivity mode.

In NR, a UE 120 may connect to an LTE cell and an NR cell using dualconnectivity. For example, the UE 120 may operate in an EvolvedUniversal Terrestrial Radio Access (EUTRA) New Radio (NR) DualConnectivity (ENDC or EN-DC) mode. In the ENDC mode, the UE 120 maycommunicate using an LTE RAT for a master cell group (e.g., including aprimary cell) and may communicate using an NR RAT for a secondary cellgroup (e.g., including one or more secondary cells). In some cases, a UE120 operating in an ENDC mode may also operate in a single transmissionmode, where the UE 120 is only capable of transmitting a single uplinktransmission at a time. The UE 120 may be a type 1 UE that is capable ofusing dynamic power sharing for uplink transmissions, or may be a type 2UE that is not capable of using dynamic power sharing for uplinktransmissions. In some cases, the single transmission mode may bereferred to as single transmission (tx) switched uplink.

In some cases, the LTE primary cell (PCell) (e.g., in the master cellgroup) may be configured with frame structure type 2, which usestime-division duplexing (TDD). Thus, the UE 120 may operate using singletransmission switched uplink in ENDC with a TDD PCell. In this case, theUE 120 may be configured with a TDD UL/DL configuration (e.g., for theLTE PCell) that indicates a pattern of uplink (UL) subframes, downlink(DL) subframes, and/or special (S) subframes (e.g., for switchingbetween UL and DL subframes) in a radio frame. The UE 120 may also beconfigured with a downlink-reference uplink-downlink configuration(sometimes referred to as a DL-reference UL/DL configuration or aDL-reference UL-DL configuration). The DL-reference UL/DL configurationmay indicate a timing for hybrid automatic repeat request (HARQ)feedback (e.g., on the LTE PCell) for a physical downlink shared channel(PDSCH) on the serving cell. HARQ feedback for the PDSCH may sometimesbe referred to as acknowledgement (ACK) or negative acknowledgement(NACK) (collectively, ACK/NACK) feedback. For example, the DL-referenceUL/DL configuration may indicate one or more uplink subframes of the TDDUL/DL configuration that are designated as uplink subframes for HARQfeedback of downlink LTE communications. The subframes designated asuplink subframes for HARQ feedback by the DL-reference UL/DLconfiguration may be referred to herein as uplink subframes designatedas uplink.

As shown by reference number 305, in example 300, a type 1 UE (e.g.,with a dynamic power sharing capability) is configured with LTE TDDUL/DL configuration #1, which has an UL/DL/S subframe pattern of D, S,U, U, D, D, S, U, U, D (two consecutive frames with this pattern areshown). Furthermore, as shown by reference number 310, the type 1 UE isconfigured with DL-reference UL/DL configuration #4, which indicatesthat HARQ feedback subframes 1 through 4 (shown as S, U, U, D) of aframe are to be transmitted in subframe 8 of the frame, and that HARQfeedback for subframes 5 through 9 of a prior frame (Frame X) andsubframe 0 of the current frame (Frame X+1) (shown as D, S, U, U, D, D)are to be transmitted in subframe 7 of the frame. In this example,subframes 7 and 8 are uplink subframes designated as UL by theDL-reference UL/DL configuration. The LTE TDD UL/DL configuration andthe DL-reference UL/DL configuration described herein are provided asexamples, and the UE may be configured with another LTE TDD UL/DLconfiguration and/or another DL-reference UL/DL configuration.

As shown by reference number 315, for a type 1 UE operating in a singleuplink transmission mode in ENDC with a TDD PCell, if there is acollision between an uplink communication on LTE (e.g., an LTE physicaluplink shared channel (PUSCH) communication) and an uplink communicationon NR (e.g., an NR PUSCH communication), then the UE may drop the NRPUSCH communication and may transmit the LTE PUSCH communication. Forexample, if the UE is scheduled to transmit HARQ feedback for PDSCH inan LTE PUSCH communication in a subframe designated as UL by theDL-reference UL/DL configuration, then the UE may drop the NR PUSCHcommunication in that subframe. Because a type 1 UE has tight couplingbetween components that control NR communications and components thatcontrol LTE communications, the type 1 UE may be capable of detectingcollisions and dropping NR PUSCH communications in the event of acollision, unlike a type 2 UE described below in connection with FIG. 4.

By dropping NR PUSCH communications in favor of LTE PUSCH communicationsin the uplink subframes designated as uplink by the DL-reference UL/DLconfiguration, the UE may avoid a collision. However, other LTE uplinkcommunications, such as LTE physical random access channel (PRACH)communications, LTE sounding reference signals (SRS), and/or LTEphysical uplink control channel (PUCCH) communications (e.g., includinga scheduling request (SR), channel state information (CSI) feedback,and/or the like), may be handled differently (e.g., due to differentpriorities). If such LTE UL communications are permitted on all ULsubframes of the LTE TDD UL/DL configuration (e.g., regardless ofwhether those UL subframes are designated as UL by the DL-referenceUL/DL configuration), then the opportunities for NR uplinkcommunications may be highly limited due to the number of such LTE ULcommunications, thereby degrading NR performance. However, if such LTEUL communications are limited to UL subframes designated as UL by theDL-reference UL/DL configuration, then the opportunity for transmissionof such LTE UL communications may be limited (e.g., to two subframes inexample 300), which may degrade performance of LTE communications andcause interference and congestion on the UL subframes designated as ULby the DL-reference UL/DL configuration. Some techniques and apparatusesdescribed herein address these and other issues, and permit flexible andefficient transmission of uplink communications for a UE operating in asingle transmission mode in ENDC with a TDD PCell.

As indicated above, FIG. 3 is provided merely as an example. Otherexamples may differ from what is described with regard to FIG. 3.

FIG. 4 is a diagram illustrating an example 400 of behavior of a type 2UE (e.g., a UE without a dynamic power sharing capability) for handlingsingle uplink transmissions in a dual connectivity mode.

As shown by reference number 405, in example 400, a type 2 UE (e.g.,without a dynamic power sharing capability) is configured with LTE TDDUL/DL configuration #1, as described above in connection with FIG. 3.Furthermore, as shown by reference number 410, the type 2 UE isconfigured with DL-reference UL/DL configuration #4, as described abovein connection with FIG. 3.

As shown by reference number 415, for a type 2 UE operating in a singleuplink transmission mode in ENDC with a TDD PCell, a first group ofsubframes may be reserved for and/or available for NR PUSCHcommunications (e.g., subframes 0 through 6 and subframe 9) and a secondgroup of subframes (e.g., subframes 7 and 8) may be reserved for and/oravailable for LTE PUSCH communications. Because a type 2 UE does nothave tight coupling between components that control NR communicationsand components that control LTE communications, the type 2 UE may not becapable of detecting collisions and dropping NR PUSCH communications inthe event of a collision, as described above in connection with a type 1UE.

In this configuration, the opportunity for LTE PUSCH communications maybe limited (e.g., to two subframes), which may degrade LTE performance.Furthermore, the type 2 UE is not capable of transmitting NR PUSCHcommunications in the UL subframes designated as UL by the DL-referenceUL/DL configuration (e.g., subframes 7 and 8 of example 400), even ifthe type 2 UE is not scheduled to transmit an LTE PUSCH communication inthose UL subframes, which wastes network resources, reduces spectralefficiency, and degrades NR performance.

Also, as described above in connection with FIG. 3, other LTE uplinkcommunications, such as LTE PRACH communications, LTE SRSs, and/or LTEPUCCH communications, may be handled differently (e.g., due to differentpriorities). If such LTE UL communications are permitted on all ULsubframes of the LTE TDD UL/DL configuration, then the opportunities forNR uplink communications may be highly limited due to the number of suchLTE UL communications, thereby degrading NR performance. However, ifsuch LTE UL communications are limited to UL subframes designated as ULby the DL-reference UL/DL configuration, then the opportunity fortransmission of such LTE UL communications may be limited (e.g., to twosubframes in example 400), which may degrade performance of LTEcommunications. Some techniques and apparatuses described herein addressthese and other issues, and permit flexible and efficient transmissionof uplink communications for a UE operating in a single transmissionmode in ENDC with a TDD PCell.

As indicated above, FIG. 4 is provided merely as an example. Otherexamples may differ from what is described with regard to FIG. 4.

FIG. 5 is a diagram illustrating an example 500 of handling singleuplink transmissions in a dual connectivity mode, in accordance withvarious aspects of the present disclosure.

As shown in FIG. 5, a type 1 UE (e.g., UE 120) may be configured with aTDD UL/DL configuration (e.g., for an LTE PCell) that indicates apattern of UL subframes, DL subframes, and/or S subframes in an LTEradio frame, as described above. As further shown, the UE may also beconfigured with a DL-reference UL/DL configuration, as described above.As shown, the DL-reference UL/DL configuration may indicate one or moreuplink subframes of the TDD UL/DL configuration that are designated asuplink subframes for HARQ feedback of downlink LTE communications. Inexample 500, the UE is configured with LTE TDD UL/DL configuration #1and DL-reference UL/DL configuration #4, as described above inconnection with FIG. 3. The TDD UL/DL configuration and/or theDL-reference UL/DL configuration may be indicated to the UE by a basestation 110, such as in a system information block (SIB), a radioresource control (RRC) message, and/or the like.

As shown by reference number 505, for a type 1 UE operating in a singleuplink transmission mode in ENDC with a TDD PCell, if there is acollision between an uplink communication on LTE and an uplinkcommunication on NR, then the UE may drop the NR uplink communicationand may transmit the LTE uplink communication. In some aspects, the LTEuplink communication may include an LTE PUSCH communication, an LTEPUCCH communication, an LTE PRACH communication, an LTE SRS, and/or thelike. Similarly, the NR uplink communication may include an NR PUSCHcommunication, an NR PUCCH communication, an NR PRACH communication, anNR SRS, and/or the like. By dropping NR uplink communications in favorof LTE uplink communications in the uplink subframes designated asuplink by the DL-reference UL/DL configuration, the UE may avoid acollision. However, this may degrade NR performance.

As indicated above, FIG. 5 is provided merely as an example. Otherexamples may differ from what is described with regard to FIG. 5.

FIG. 6 is a diagram illustrating an example 600 of handling singleuplink transmissions in a dual connectivity mode, in accordance withvarious aspects of the present disclosure. As shown in FIG. 6, a type 1UE (e.g., UE 120) and a base station 110 may communicate with oneanother. In example 600, the UE may operate in a single transmissionswitched uplink mode, may have a dynamic power sharing capability, andmay be configured with an LTE PCell (or a PCell of a first radio accesstechnology (RAT)) that uses frame structure type 2 (e.g., TDD).

As shown in FIG. 6, the type 1 UE may be configured with a TDD UL/DLconfiguration for an LTE PCell and may be configured with a DL-referenceUL/DL configuration, as described above. As shown, the DL-referenceUL/DL configuration may indicate one or more uplink subframes of the TDDUL/DL configuration that are designated as uplink. In example 600, theUE is configured with LTE TDD UL/DL configuration #1 and DL-referenceUL/DL configuration #4, as described above in connection with FIG. 3.The TDD UL/DL configuration and/or the DL-reference UL/DL configurationmay be indicated to the UE by the base station 110, such as in a SIB, anRRC message, and/or the like.

As shown by reference number 605, the UE may be in an ENDC mode with oneor more base stations 110. In some aspects, the UE may operate in theENDC mode via a connection with a first base station 110 that operatesusing a first radio access technology (RAT) and a connection with asecond base station 110 that operates using a second RAT. Alternatively,the UE may operate in the ENDC mode via multiple connections with asingle base station 110 capable of multi-RAT operation. In the ENDCmode, the first RAT is an LTE RAT and the second RAT is an NR RAT, andone or more cells of the LTE RAT are configured in a master cell group(MCG), while one or more cells of the NR RAT are configured in asecondary cell group (SCG). Although some aspects are described hereinin connection with an ENDC mode with the LTE RAT being associated withan MCG and the NR RAT being associated with an SCG, these aspects mayapply to other types of dual connectivity modes with a first RAT beingassociated with an MCG and a second RAT being associated with an SCG.

As shown by reference number 610, the UE may determine whether an uplinkcommunication for the first RAT (e.g., an LTE RAT in example 600) hasbeen dynamically scheduled or semi-statically configured. In someaspects, an uplink communication may be dynamically scheduled if theuplink communication is scheduled by downlink control information (DCI).Additionally, or alternatively, a dynamically scheduled uplinkcommunication may include a PUSCH communication scheduled by DCI (e.g.,which may exclude PUSCH communications scheduled using a configuredgrant indicated in an RRC message), an aperiodic SRS, and/or the like.

In some aspects, an uplink communication may be semi-staticallyconfigured if the uplink communication is configured by an RRC message,a medium access control (MAC) control element (CE) (MAC-CE), and/or thelike. Additionally, or alternatively, a semi-statically configureduplink communication may include a PUSCH communication scheduled by anRRC message (e.g., using a configured grant), a periodic SRS, asemi-persistent SRS, a PUCCH communication (e.g., a PUCCH communicationthat includes CSI, a PUCCH communication that includes a schedulingrequest, and/or the like), a PRACH communication, and/or the like.

In some aspects, different types of PRACH communications may beconsidered dynamically scheduled or semi-statically configured. Forexample, a dynamically scheduled uplink communication may include aPRACH communication for contention-free random access (CFRA), a physicaldownlink control channel (PDCCH)-ordered PRACH communication (e.g., aPRACH communication scheduled by DCI or a PDCCH-order), and/or the like.As another example, a semi-statically configured uplink communicationmay include a PRACH communication for contention-based random access(CBRA). Alternatively, a dynamically configured uplink communication mayinclude a PRACH communication for CBRA.

As shown by reference number 615, the UE may identify an uplink subframefor transmission of the uplink communication based at least in part onwhether the uplink communication has been dynamically scheduled orsemi-statically configured. Additionally, or alternatively, the UE mayidentify the uplink subframe based at least in part on a DL-referenceUL/DL configuration. For example, if the uplink communication isdynamically scheduled, then any uplink subframe of the TDD UL/DLconfiguration may be used for transmission of the uplink communicationregardless of whether the uplink subframe is designated as uplink by theDL-reference UL/DL configuration. In this case, uplink subframes 2, 3,7, and 8 are available for transmission of dynamically scheduled uplinkcommunications in example 600. Additionally, or alternatively, if theuplink communication is semi-statically configured, then only uplinksubframes of the TDD UL/DL configuration that are designated as uplinkby the DL-reference UL/DL configuration may be used for transmission ofthe uplink communication. In this case, uplink subframes 7 and 8 (andnot 2 and 3) are available for transmission of semi-staticallyconfigured uplink communications.

Thus, if the uplink communication is dynamically scheduled, then theuplink communication is not limited to uplink subframes (e.g., of theTDD UL/DL configuration) designated as uplink by the DL-reference UL/DLconfiguration. Conversely, if the uplink communication issemi-statically configured, then the uplink communication is limited touplink subframes designated as uplink by the DL-reference UL/DLconfiguration. As a result, a first set of uplink subframes, permittedfor transmission of the uplink communication when the uplinkcommunication is dynamically scheduled, may be different from a secondset of uplink subframes permitted for transmission of the uplinkcommunication when the uplink communication is semi-staticallyconfigured. For example, the first set of uplink subframes may includeuplink subframes designated as uplink by the DL-reference UL/DLconfiguration and may also include uplink subframes not designated asuplink by the DL-reference UL/DL configuration, while the second set ofuplink subframes may include uplink subframes designated as uplink bythe DL-reference UL/DL configuration and may exclude uplink subframesnot designated as uplink by the DL-reference UL/DL configuration. Inexample 600, the first set of uplink subframes includes only subframes2, 3, 7, and 8, and the second set of uplink subframes includes onlysubframes 7 and 8.

As shown by reference number 620, the UE may transmit the uplinkcommunication in the identified uplink subframe. In some aspects, if theuplink communication is scheduled and/or configured to occur in theidentified uplink subframe (e.g., a permitted uplink subframe, dependingon whether the uplink communication is dynamically scheduled orsemi-statically configured), then the UE may transmit the uplinkcommunication in the identified uplink subframe. Alternatively, if theuplink communication is scheduled and/or configured to occur in adifferent subframe than an identified subframe (e.g., an uplink subframein which transmission is not permitted, depending on whether the uplinkcommunication is dynamically scheduled or semi-statically configured),then the UE may drop the uplink communication in the identified uplinksubframe.

By permitting the UE to identify an uplink subframe, for an uplinkcommunication, from different sets of uplink subframes depending onwhether the uplink communication is dynamically scheduled orsemi-statically configured, performance of LTE and NR may be balanced.For example, the base station 110 and the UE may have increasedflexibility for dynamic scheduling of uplink communication in LTE. Thisincreased flexibility may result in lower performance degradation of NRthan allowing semi-statically configured uplink communications to betransmitted in any uplink subframe, because there are typically fewerdynamically scheduled uplink communications than semi-staticallyconfigured uplink communications. By limiting semi-statically configureduplink communications to subframes designated as uplink by theDL-reference UL/DL configuration, NR performance degradation may not beimpacted by these semi-statically configured uplink communications,which are typically more numerous and periodic than dynamicallyscheduled uplink communications. In some aspects, performance may befurther improved by multiplexing some uplink communications that wouldotherwise be dropped, as described below in connection with FIG. 7.

As indicated above, FIG. 6 is provided merely as an example. Otherexamples may differ from what is described with regard to FIG. 6.

FIG. 7 is a diagram illustrating another example 700 of handling singleuplink transmissions in a dual connectivity mode, in accordance withvarious aspects of the present disclosure.

As shown by reference number 705, a UE may be configured with periodicCSI, which is considered a semi-statically configured uplinkcommunication. For example, an RRC message (e.g., an RRC configurationmessage, an RRC reconfiguration message, and/or the like) may configurethe periodic CSI and a corresponding periodicity. As described above inconnection with FIG. 6, because the periodic CSI is semi-staticallyconfigured, the uplink subframes in which the periodic CSI is permittedto be transmitted may be limited to uplink subframes designated asuplink by the DL-reference UL/DL configuration. Thus, as shown byreference number 710, if a periodic CSI is configured to occur in anuplink subframe designated as uplink by the DL-reference UL/DLconfiguration, then the UE may transmit the periodic CSI. Also, the UEmay drop periodic CSI configured to occur (e.g., according to aconfigured periodicity) in an uplink subframe that is not designated asuplink by the DL-reference UL/DL configuration.

However, if a dynamically scheduled PUSCH communication is scheduled tooccur in the uplink subframe in which the periodic CSI is configured tooccur (e.g., an uplink subframe that is not designated as uplink by theDL-reference UL/DL configuration), then the UE may multiplex (e.g.,piggyback) the periodic CSI in the PUSCH communication. For example, asshown by reference number 715, if a dynamically scheduled PUSCHcommunication is scheduled to occur in the same uplink subframe asperiodic CSI, and that uplink subframe is not designated as uplink bythe DL-reference UL/DL configuration, then the UE may multiplex (e.g.,piggyback) the periodic CSI with the PUSCH communication (e.g., maytransmit the periodic CSI on the PUSCH). In some aspects, the UE maymultiplex the periodic CSI with a PUSCH communication regardless ofwhether the PUSCH communication is scheduled to be transmitted in anuplink subframe designated as uplink or an uplink subframe notdesignated as uplink.

As shown by reference number 720, if a periodic CSI is scheduled tooccur in an uplink subframe not designated as uplink by the DL-referenceUL/DL configuration, and there is not a PUSCH communication scheduled tooccur in the same uplink subframe as the periodic CSI, then the UE maydrop the periodic CSI.

In this way, performance may be improved by multiplexing some uplinkcommunications that would otherwise be dropped (e.g., periodic CSI).Although FIG. 7 is described in connection with periodic CSI, in someaspects, other types of dynamically scheduled uplink communications maybe multiplexed with a PUSCH communication in the manner described hereinin connection with FIG. 7.

As indicated above, FIG. 7 is provided merely as an example. Otherexamples may differ from what is described with regard to FIG. 7.

FIG. 8 is a diagram illustrating another example 800 of handling singleuplink transmissions in a dual connectivity mode, in accordance withvarious aspects of the present disclosure. As shown in FIG. 8, a type 2UE (e.g., UE 120) and a base station 110 may communicate with oneanother. In example 800, the UE may operate in a single transmissionswitched uplink mode, may not have a dynamic power sharing capability,and may be configured with an LTE PCell (or a PCell of a first RAT) thatuses frame structure type 2 (e.g., TDD).

As shown in FIG. 8, the type 2 UE may be configured with a TDD UL/DLconfiguration for an LTE PCell and may be configured with a DL-referenceUL/DL configuration, as described above. As shown, the DL-referenceUL/DL configuration may indicate one or more uplink subframes of the TDDUL/DL configuration that are designated as uplink. In example 800, theUE is configured with LTE TDD UL/DL configuration #1 and DL-referenceUL/DL configuration #4, as described above in connection with FIGS. 3and 4. The TDD UL/DL configuration and/or the DL-reference UL/DLconfiguration may be indicated to the UE by the base station 110, suchas in a SIB, an RRC message, and/or the like.

As shown by reference number 805, the UE may be in an ENDC mode with oneor more base stations 110, as described above in connection with FIG. 6.In the ENDC mode, the first RAT is an LTE RAT and the second RAT is anNR RAT, and one or more cells of the LTE RAT are configured in an MCG,while one or more cells of the NR RAT are configured in an SCG. Althoughsome aspects are described herein in connection with an ENDC mode withthe LTE RAT being associated with an MCG and the NR RAT being associatedwith an SCG, these aspects may apply to other types of dual connectivitymodes with a first RAT being associated with an MCG and a second RATbeing associated with an SCG.

As shown by reference number 810, the UE may determine a type of anuplink communication (e.g., an uplink communication type) for the firstRAT (e.g., an LTE RAT in example 800). Example uplink communicationtypes include PUSCH communications, PUCCH communications, PRACHcommunications, SRSs, and/or the like.

As shown by reference number 815, the UE may identify a subframe fortransmission of the uplink communication based at least in part on theuplink communication type. Additionally, or alternatively, the UE mayidentify the subframe based at least in part on a DL-reference UL/DLconfiguration. For example, if the uplink communication is a first typeof uplink communication (e.g., a PUSCH communication and/or a PUCCHcommunication), then only uplink subframes of the TDD UL/DLconfiguration that are designated as uplink by the DL-reference UL/DLconfiguration may be used for transmission of the uplink communication.In this case, only uplink subframes 7 and 8 are available fortransmission of the first type of uplink communication (e.g., PUSCHcommunications and/or PUCCH communications) in example 800.

Additionally, or alternatively, if the uplink communication is a secondtype of uplink communication (e.g., a PRACH communication and/or anSRS), then uplink subframes of the TDD UL/DL configuration that aredesignated as uplink may be used for transmission of the uplinkcommunication, and special subframes that immediately precede an uplinksubframe designated as uplink may also be used for transmission of theuplink communication. For example, the UE may use an uplink pilot timeslot (UpPTS) of a special subframe, that immediately precedes an uplinksubframe designated as uplink, for transmission of the second type ofuplink communications. In this case, uplink subframes 7 and 8, as wellas the UpPTS of special subframe 6, are available for transmission ofthe second type of uplink communication (e.g., PRACH communicationsand/or SRSs) in example 800. However, the UpPTS of special subframe 1 isnot available for transmission of the second type of uplinkcommunication, because special subframe 1 does not immediately precedean uplink subframe designated as uplink (e.g., special subframe 1immediately precedes an uplink subframe not designated as uplink by theDL-reference UL/DL configuration).

Thus, if the uplink communication is a first type of communication, suchas a PUSCH communication or a PUCCH communication, then the uplinkcommunication is limited to uplink subframes (e.g., of the TDD UL/DLconfiguration) designated as uplink by the DL-reference UL/DLconfiguration. However, if the uplink communication is a second type ofcommunication, such as a PRACH communication or an SRS, then the uplinkcommunication is limited to a set of subframes that includes uplinksubframes designated as uplink by the DL-reference UL/DL configurationand special subframes that immediately precede an uplink subframedesignated as uplink by the DL-reference UL/DL configuration. As aresult, a first set of subframes, permitted for transmission of a firsttype of uplink communication, may be different from a second set ofsubframes permitted for transmission of a second type of uplinkcommunication. In example 800, the first set of uplink subframesincludes only subframes 7 and 8, and the second set of uplink subframesincludes only subframes 6 (e.g., an UpPTS of subframe 6), 7, and 8.

As shown by reference number 820, the UE may transmit the uplinkcommunication in the identified subframe. In some aspects, if the uplinkcommunication is scheduled and/or configured to occur in the identifiedsubframe (e.g., a permitted subframe, depending on whether the uplinkcommunication is a first type of uplink communication or second type ofuplink communication), then the UE may transmit the uplink communicationin the identified subframe. Alternatively, if the uplink communicationis scheduled and/or configured to occur in a different subframe than anidentified subframe (e.g., a subframe in which transmission is notpermitted, depending on whether the uplink communication is a first typeof uplink communication or second type of uplink communication), thenthe UE may drop the uplink communication in the identified subframe.

By permitting transmission of the second type of uplink communication(e.g., PRACH communications and/or SRSs) to UpPTSs of special subframesthat immediately precede an uplink subframe designated as uplink,transmission opportunities for the second type of communication may beincreased while avoiding frequent switching between LTE and NR.

As indicated above, FIG. 8 is provided merely as an example. Otherexamples may differ from what is described with regard to FIG. 8.

FIG. 9 is a diagram illustrating another example 900 of handling singleuplink transmissions in a dual connectivity mode, in accordance withvarious aspects of the present disclosure. As shown in FIG. 9, a type 2UE (e.g., UE 120) and a base station 110 may communicate with oneanother. In example 900, the UE may operate in a single transmissionswitched uplink mode, may not have a dynamic power sharing capability,and may be configured with an LTE PCell (or a PCell of a first RAT) thatuses frame structure type 2 (e.g., TDD).

As shown in FIG. 9, the type 2 UE may be configured with a TDD UL/DLconfiguration for an LTE PCell and may be configured with a DL-referenceUL/DL configuration, as described above. As shown, the DL-referenceUL/DL configuration may indicate one or more uplink subframes of the TDDUL/DL configuration that are designated as uplink. In example 900, theUE is configured with LTE TDD UL/DL configuration #1 and DL-referenceUL/DL configuration #4, as described above in connection with FIGS. 3and 4. The TDD UL/DL configuration and/or the DL-reference UL/DLconfiguration may be indicated to the UE by the base station 110, suchas in a SIB, an RRC message, and/or the like.

As shown by reference number 905, the UE may be in an ENDC mode with oneor more base stations 110, as described above in connection with FIG. 6.In the ENDC mode, the first RAT is an LTE RAT and the second RAT is anNR RAT, and one or more cells of the LTE RAT are configured in an MCG,while one or more cells of the NR RAT are configured in an SCG. Althoughsome aspects are described herein in connection with an ENDC mode withthe LTE RAT being associated with an MCG and the NR RAT being associatedwith an SCG, these aspects may apply to other types of dual connectivitymodes with a first RAT being associated with an MCG and a second RATbeing associated with an SCG.

As shown by reference number 910, the UE may identify one or moresymbols, in an uplink subframe designated as uplink by the DL-referenceUL/DL configuration, in which the UE is not permitted to transmit anuplink communication for the first RAT (e.g., an LTE uplinkcommunication). In some aspects, the UE may identify the one or moresymbols based at least in part on upper layer signaling, such as systeminformation (e.g., a SIB and/or the like), an RRC message, and/or thelike. In some aspects, the one or more symbols may be configured forcell-specific SRS in LTE. For example, the one or more symbols may beconfigured for cell-specific SRS for one or more other UEs, and the UEmay blank or may mute transmissions (e.g., may refrain fromtransmitting) in the one or more symbols to reduce interference with SRStransmitted by the other UE(s). In example 900, an LTE cell-specific SRSis configured in the last symbol of each of subframes 7 and 8.

As shown by reference number 915, the UE may transmit an uplinkcommunication for the second RAT (e.g., an NR uplink communication) inthe identified symbol(s). Because the UE is configured to blank or muteLTE uplink transmissions on the one or more symbols, spectral efficiencymay be improved by using those one or more symbols for NR uplinktransmissions.

As indicated above, FIG. 9 is provided merely as an example. Otherexamples may differ from what is described with regard to FIG. 9.

FIG. 10 is a diagram illustrating an example process 1000 performed, forexample, by a UE, in accordance with various aspects of the presentdisclosure. Example process 1000 is an example where a UE (e.g., UE 120and/or the like) performs operations associated with handling singleuplink transmissions in a dual connectivity mode.

As shown in FIG. 10, in some aspects, process 1000 may includedetermining whether an uplink communication for a first RAT has beendynamically scheduled or semi-statically configured, wherein the UE isin a dual connectivity mode using the first RAT and a second RAT (block1010). For example, the UE (e.g., using receive processor 258, transmitprocessor 264, controller/processor 280, memory 282, and/or the like)may determine whether an uplink communication for a first RAT has beendynamically scheduled or semi-statically configured, as described above.In some aspects, the UE is in a dual connectivity mode using the firstRAT and a second RAT.

As further shown in FIG. 10, in some aspects, process 1000 may includeidentifying an uplink subframe for transmission of the uplinkcommunication based at least in part on whether the uplink communicationhas been dynamically scheduled or semi-statically configured, and basedat least in part on a downlink-reference uplink-downlink configuration(block 1020). For example, the UE (e.g., using receive processor 258,transmit processor 264, controller/processor 280, memory 282, and/or thelike) may identify an uplink subframe for transmission of the uplinkcommunication based at least in part on whether the uplink communicationhas been dynamically scheduled or semi-statically configured, and basedat least in part on a downlink-reference uplink-downlink configuration,as described above.

As further shown in FIG. 10, in some aspects, process 1000 may includetransmitting the uplink communication in the identified uplink subframe(block 1030). For example, the UE (e.g., using transmit processor 264,controller/processor 280, memory 282, and/or the like) may transmit theuplink communication in the identified uplink subframe, as describedabove.

Process 1000 may include additional aspects, such as any single aspector any combination of aspects described below and/or in connection withone or more other processes described elsewhere herein.

In a first aspect, the UE is in a single transmission switched uplinkmode, the UE has a dynamic power sharing capability, and a primary cellof the first RAT uses frame structure type 2.

In a second aspect, alone or in combination with the first aspect, theidentified uplink subframe is not limited to uplink subframes designatedas uplink by the downlink-reference uplink-downlink configuration if theuplink communication has been dynamically scheduled.

In a third aspect, alone or in combination with one or more of the firstand second aspects, the identified uplink subframe is limited to uplinksubframes designated as uplink by the downlink-reference uplink-downlinkconfiguration if the uplink communication has been semi-staticallyconfigured.

In a fourth aspect, alone or in combination with one or more of thefirst through third aspects, a first set of uplink subframes, permittedfor transmission of the uplink communication when the uplinkcommunication is dynamically scheduled, is different from a second setof uplink subframes permitted for transmission of the uplinkcommunication when the uplink communication is semi-staticallyconfigured.

In a fifth aspect, alone or in combination with one or more of the firstthrough fourth aspects, the first set of uplink subframes includesuplink subframes designated as uplink by the downlink-referenceuplink-downlink configuration, and also includes uplink subframes notdesignated as uplink by the downlink-reference uplink-downlinkconfiguration.

In a sixth aspect, alone or in combination with one or more of the firstthrough fifth aspects, the second set of uplink subframes includesuplink subframes designated as uplink by the downlink-referenceuplink-downlink configuration, and excludes uplink subframes notdesignated as uplink by the downlink-reference uplink-downlinkconfiguration.

In a seventh aspect, alone or in combination with one or more of thefirst through sixth aspects, the identified uplink subframe is notlimited to uplink subframes designated as uplink by thedownlink-reference uplink-downlink configuration if the uplinkcommunication has been scheduled by downlink control information.

In an eighth aspect, alone or in combination with one or more of thefirst through seventh aspects, the identified uplink subframe is limitedto uplink subframes designated as uplink by the downlink-referenceuplink-downlink configuration if the uplink communication has beenconfigured by at least one of a radio resource control message or amedium access control message.

In a ninth aspect, alone or in combination with one or more of the firstthrough eighth aspects, the identified uplink subframe is not limited touplink subframes designated as uplink by the downlink-referenceuplink-downlink configuration if the uplink communication is a physicaluplink shared channel communication scheduled by downlink controlinformation or is an aperiodic sounding reference signal.

In a tenth aspect, alone or in combination with one or more of the firstthrough ninth aspects, the identified uplink subframe is limited touplink subframes designated as uplink by the downlink-referenceuplink-downlink configuration if the uplink communication is aconfigured grant physical uplink shared channel communication, aperiodic or semi-persistent sounding reference signal, a physical uplinkcontrol channel communication, or a physical random access channelcommunication.

In an eleventh aspect, alone or in combination with one or more of thefirst through tenth aspects, the identified uplink subframe is limitedto uplink subframes designated as uplink by the downlink-referenceuplink-downlink configuration if the uplink communication is a PUCCHcommunication that includes channel state information or a schedulingrequest.

In a twelfth aspect, alone or in combination with one or more of thefirst through eleventh aspects, the identified uplink subframe is notlimited to uplink subframes designated as uplink by thedownlink-reference uplink-downlink configuration if the uplinkcommunication is at least one of a PRACH communication forcontention-free random access or a PDCCH-ordered PRACH communication.

In a thirteenth aspect, alone or in combination with one or more of thefirst through twelfth aspects, the identified uplink subframe is limitedto uplink subframes designated as uplink by the downlink-referenceuplink-downlink configuration if the uplink communication is a physicalrandom access channel communication for contention-based random access.

In a fourteenth aspect, alone or in combination with one or more of thefirst through thirteenth aspects, the identified uplink subframe is notlimited to uplink subframes designated as uplink by thedownlink-reference uplink-downlink configuration if the uplinkcommunication is a physical random access channel communication forcontention-based random access.

In a fifteenth aspect, alone or in combination with one or more of thefirst through fourteenth aspects, the uplink communication is adynamically scheduled PUSCH communication and the identified uplinksubframe is not designated as uplink by the downlink-referenceuplink-downlink configuration, and the UE is configured to multiplexperiodic channel state information, configured in the identified uplinksubframe, with the PUSCH communication.

In a sixteenth aspect, alone or in combination with one or more of thefirst through fifteenth aspects, one or more cells of the first RAT areconfigured in a first cell group and one or more cells of the second RATare configured in a second cell group.

Although FIG. 10 shows example blocks of process 1000, in some aspects,process 1000 may include additional blocks, fewer blocks, differentblocks, or differently arranged blocks than those depicted in FIG. 10.Additionally, or alternatively, two or more of the blocks of process1000 may be performed in parallel.

FIG. 11 is a diagram illustrating an example process 1100 performed, forexample, by a UE, in accordance with various aspects of the presentdisclosure. Example process 1100 is an example where a UE (e.g., UE 120and/or the like) performs operations associated with handling singleuplink transmissions in a dual connectivity mode.

As shown in FIG. 11, in some aspects, process 1100 may includedetermining a type of an uplink communication for a first RAT, whereinthe UE is in a dual connectivity mode using the first RAT and a secondRAT (block 1110). For example, the UE (e.g., using receive processor258, transmit processor 264, controller/processor 280, memory 282,and/or the like) may determine a type of an uplink communication for afirst RAT, as described above. In some aspects, the UE is in a dualconnectivity mode using the first RAT and a second RAT.

As further shown in FIG. 11, in some aspects, process 1100 may includeidentifying a subframe for transmission of the uplink communicationbased at least in part on the type of the uplink communication and basedat least in part on a downlink-reference uplink-downlink configuration(block 1120). For example, the UE (e.g., using receive processor 258,transmit processor 264, controller/processor 280, memory 282, and/or thelike) may identify a subframe for transmission of the uplinkcommunication based at least in part on the type of the uplinkcommunication and based at least in part on a downlink-referenceuplink-downlink configuration, as described above.

As further shown in FIG. 11, in some aspects, process 1100 may includetransmitting the uplink communication in the identified subframe (block1130). For example, the UE (e.g., using transmit processor 264,controller/processor 280, memory 282, and/or the like) may transmit theuplink communication in the identified subframe, as described above.

Process 1100 may include additional aspects, such as any single aspector any combination of aspects described below and/or in connection withone or more other processes described elsewhere herein.

In a first aspect, the UE is in a single transmission switched uplinkmode, the UE does not have a dynamic power sharing capability, and aprimary cell of the first RAT uses frame structure type 2.

In a second aspect, alone or in combination with the first aspect, theidentified subframe is limited to uplink subframes designated as uplinkby the downlink-reference uplink-downlink configuration if the uplinkcommunication is a physical uplink shared channel communication or aphysical uplink control channel communication.

In a third aspect, alone or in combination with one or more of the firstand second aspects, the identified subframe is limited to uplinksubframes designated as uplink by the downlink-reference uplink-downlinkconfiguration or to special subframes that immediately precede an uplinksubframe designated as uplink by the downlink-reference uplink-downlinkconfiguration if the uplink communication is a sounding reference signalor a physical random access channel communication.

In a fourth aspect, alone or in combination with one or more of thefirst through third aspects, the uplink communication is transmitted inan uplink pilot time slot of a special subframe that immediatelyprecedes an uplink subframe designated as uplink by thedownlink-reference uplink-downlink configuration.

In a fifth aspect, alone or in combination with one or more of the firstthrough fourth aspects, one or more cells of the first RAT areconfigured in a first cell group and one or more cells of the second RATare configured in a second cell group.

Although FIG. 11 shows example blocks of process 1100, in some aspects,process 1100 may include additional blocks, fewer blocks, differentblocks, or differently arranged blocks than those depicted in FIG. 11.Additionally, or alternatively, two or more of the blocks of process1100 may be performed in parallel.

FIG. 12 is a diagram illustrating an example process 1200 performed, forexample, by a UE, in accordance with various aspects of the presentdisclosure. Example process 1200 is an example where a UE (e.g., UE 120and/or the like) performs operations associated with handling singleuplink transmissions in a dual connectivity mode.

As shown in FIG. 12, in some aspects, process 1200 may includeidentifying one or more symbols, in an uplink subframe designated asuplink by a downlink-reference uplink-downlink configuration, in whichthe UE is not permitted to transmit an uplink communication for a firstRAT, wherein the UE is in a dual connectivity mode using the first RATand a second RAT (block 1210). For example, the UE (e.g., using receiveprocessor 258, transmit processor 264, controller/processor 280, memory282, and/or the like) may identify one or more symbols, in an uplinksubframe designated as uplink by a downlink-reference uplink-downlinkconfiguration, in which the UE is not permitted to transmit an uplinkcommunication for a first RAT, as described above. In some aspects, theUE is in a dual connectivity mode using the first RAT and a second RAT.

As further shown in FIG. 12, in some aspects, process 1200 may includetransmitting an uplink communication for the second RAT in theidentified one or more symbols (block 1220). For example, the UE (e.g.,using transmit processor 264, controller/processor 280, memory 282,and/or the like) may transmit an uplink communication for the second RATin the identified one or more symbols, as described above.

Process 1200 may include additional aspects, such as any single aspector any combination of aspects described below and/or in connection withone or more other processes described elsewhere herein.

In a first aspect, the UE is in a single transmission switched uplinkmode, the UE does not have a dynamic power sharing capability, and aprimary cell of the first RAT uses frame structure type 2.

In a second aspect, alone or in combination with the first aspect, theone or more symbols are identified based at least in part on upper layersignaling.

In a third aspect, alone or in combination with one or more of the firstand second aspects, the upper layer signaling includes at least one ofsystem information or a radio resource control message.

In a fourth aspect, alone or in combination with one or more of thefirst through third aspects, the one or more symbols are configured forcell-specific sounding reference signals.

In a fifth aspect, alone or in combination with one or more of the firstthrough fourth aspects, one or more cells of the first RAT areconfigured in a first cell group and one or more cells of the second RATare configured in a second cell group.

Although FIG. 12 shows example blocks of process 1200, in some aspects,process 1200 may include additional blocks, fewer blocks, differentblocks, or differently arranged blocks than those depicted in FIG. 12.Additionally, or alternatively, two or more of the blocks of process1200 may be performed in parallel.

The foregoing disclosure provides illustration and description, but isnot intended to be exhaustive or to limit the aspects to the preciseform disclosed. Modifications and variations may be made in light of theabove disclosure or may be acquired from practice of the aspects.

As used herein, the term “component” is intended to be broadly construedas hardware, firmware, or a combination of hardware and software. Asused herein, a processor is implemented in hardware, firmware, or acombination of hardware and software.

As used herein, satisfying a threshold may, depending on the context,refer to a value being greater than the threshold, greater than or equalto the threshold, less than the threshold, less than or equal to thethreshold, equal to the threshold, not equal to the threshold, and/orthe like.

It will be apparent that systems and/or methods described herein may beimplemented in different forms of hardware, firmware, or a combinationof hardware and software. The actual specialized control hardware orsoftware code used to implement these systems and/or methods is notlimiting of the aspects. Thus, the operation and behavior of the systemsand/or methods were described herein without reference to specificsoftware code—it being understood that software and hardware can bedesigned to implement the systems and/or methods based, at least inpart, on the description herein.

Even though particular combinations of features are recited in theclaims and/or disclosed in the specification, these combinations are notintended to limit the disclosure of various aspects. In fact, many ofthese features may be combined in ways not specifically recited in theclaims and/or disclosed in the specification. Although each dependentclaim listed below may directly depend on only one claim, the disclosureof various aspects includes each dependent claim in combination withevery other claim in the claim set. A phrase referring to “at least oneof” a list of items refers to any combination of those items, includingsingle members. As an example, “at least one of: a, b, or c” is intendedto cover a, b, c, a-b, a-c, b-c, and a-b-c, as well as any combinationwith multiples of the same element (e.g., a-a, a-a-a, a-a-b, a-a-c,a-b-b, a-c-c, b-b, b-b-b, b-b-c, c-c, and c-c-c or any other ordering ofa, b, and c).

No element, act, or instruction used herein should be construed ascritical or essential unless explicitly described as such. Also, as usedherein, the articles “a” and “an” are intended to include one or moreitems, and may be used interchangeably with “one or more.” Furthermore,as used herein, the terms “set” and “group” are intended to include oneor more items (e.g., related items, unrelated items, a combination ofrelated and unrelated items, etc.), and may be used interchangeably with“one or more.” Where only one item is intended, the phrase “only one” orsimilar language is used. Also, as used herein, the terms “has,” “have,”“having,” and/or the like are intended to be open-ended terms. Further,the phrase “based on” is intended to mean “based, at least in part, on”unless explicitly stated otherwise.

What is claimed is:
 1. A method of wireless communication performed by auser equipment (UE), comprising: determining whether an uplinkcommunication for a first radio access technology (RAT) has beendynamically scheduled or semi-statically configured, wherein the UE isin a dual connectivity mode using the first RAT and a second RAT;identifying an uplink subframe for transmission of the uplinkcommunication based at least in part on whether the uplink communicationhas been dynamically scheduled or semi-statically configured and basedat least in part on a downlink-reference uplink-downlink configuration;and transmitting the uplink communication in the identified uplinksubframe.
 2. The method of claim 1, wherein the UE is in a singletransmission switched uplink mode, the UE has a dynamic power sharingcapability, and a primary cell of the first RAT uses frame structuretype
 2. 3. The method of claim 1, wherein the identified uplink subframeis not limited to uplink subframes designated as uplink by thedownlink-reference uplink-downlink configuration if the uplinkcommunication has been dynamically scheduled.
 4. The method of claim 1,wherein the identified uplink subframe is limited to uplink subframesdesignated as uplink by the downlink-reference uplink-downlinkconfiguration if the uplink communication has been semi-staticallyconfigured.
 5. The method of claim 1, wherein a first set of uplinksubframes, permitted for transmission of the uplink communication whenthe uplink communication is dynamically scheduled, is different from asecond set of uplink subframes permitted for transmission of the uplinkcommunication when the uplink communication is semi-staticallyconfigured.
 6. The method of claim 5, wherein the first set of uplinksubframes includes uplink subframes designated as uplink by thedownlink-reference uplink-downlink configuration and also includesuplink subframes not designated as uplink by the downlink-referenceuplink-downlink configuration.
 7. The method of claim 5, wherein thesecond set of uplink subframes includes uplink subframes designated asuplink by the downlink-reference uplink-downlink configuration andexcludes uplink subframes not designated as uplink by thedownlink-reference uplink-downlink configuration.
 8. The method of claim1, wherein the identified uplink subframe is not limited to uplinksubframes designated as uplink by the downlink-reference uplink-downlinkconfiguration if the uplink communication has been scheduled by downlinkcontrol information.
 9. The method of claim 1, wherein the identifieduplink subframe is limited to uplink subframes designated as uplink bythe downlink-reference uplink-downlink configuration if the uplinkcommunication has been configured by at least one of a radio resourcecontrol message or a medium access control message.
 10. The method ofclaim 1, wherein the identified uplink subframe is not limited to uplinksubframes designated as uplink by the downlink-reference uplink-downlinkconfiguration if the uplink communication is a physical uplink sharedchannel communication scheduled by downlink control information or is anaperiodic sounding reference signal.
 11. The method of claim 1, whereinthe identified uplink subframe is limited to uplink subframes designatedas uplink by the downlink-reference uplink-downlink configuration if theuplink communication is a configured grant physical uplink sharedchannel communication, a periodic or semi-persistent sounding referencesignal, a physical uplink control channel communication, or a physicalrandom access channel communication.
 12. The method of claim 1, whereinthe identified uplink subframe is limited to uplink subframes designatedas uplink by the downlink-reference uplink-downlink configuration if theuplink communication is a physical uplink control channel (PUCCH)communication that includes channel state information or a schedulingrequest.
 13. The method of claim 1, wherein the identified uplinksubframe is not limited to uplink subframes designated as uplink by thedownlink-reference uplink-downlink configuration if the uplinkcommunication is at least one of a physical random access channel(PRACH) communication for contention-free random access or aPDCCH-ordered PRACH communication.
 14. The method of claim 1, whereinthe identified uplink subframe is limited to uplink subframes designatedas uplink by the downlink-reference uplink-downlink configuration if theuplink communication is a physical random access channel communicationfor contention-based random access.
 15. The method of claim 1, whereinthe identified uplink subframe is not limited to uplink subframesdesignated as uplink by the downlink-reference uplink-downlinkconfiguration if the uplink communication is a physical random accesschannel communication for contention-based random access.
 16. The methodof claim 1, wherein the uplink communication is a dynamically scheduledphysical uplink shared channel (PUSCH) communication and the identifieduplink subframe is not designated as uplink by the downlink-referenceuplink-downlink configuration, and wherein the UE is configured tomultiplex periodic channel state information, configured in theidentified uplink subframe, with the PUSCH communication.
 17. The methodof claim 1, wherein one or more cells of the first RAT are configured ina first cell group and one or more cells of the second RAT areconfigured in a second cell group.
 18. A method of wirelesscommunication performed by a user equipment (UE), comprising:determining a type of an uplink communication for a first radio accesstechnology (RAT), wherein the UE is in a dual connectivity mode usingthe first RAT and a second RAT; identifying a subframe for transmissionof the uplink communication based at least in part on the type of theuplink communication and based at least in part on a downlink-referenceuplink-downlink configuration; and transmitting the uplink communicationin the identified subframe.
 19. The method of claim 18, wherein the UEis in a single transmission switched uplink mode, the UE does not have adynamic power sharing capability, and a primary cell of the first RATuses frame structure type
 2. 20. The method of claim 18, wherein theidentified subframe is limited to uplink subframes designated as uplinkby the downlink-reference uplink-downlink configuration if the uplinkcommunication is a physical uplink shared channel communication or aphysical uplink control channel communication.
 21. The method of claim18, wherein the identified subframe is limited to uplink subframesdesignated as uplink by the downlink-reference uplink-downlinkconfiguration or to special subframes that immediately precede an uplinksubframe designated as uplink by the downlink-reference uplink-downlinkconfiguration if the uplink communication is a sounding reference signalor a physical random access channel communication.
 22. The method ofclaim 21, wherein the uplink communication is transmitted in an uplinkpilot time slot of a special subframe that immediately precedes anuplink subframe designated as uplink by the downlink-referenceuplink-downlink configuration.
 23. The method of claim 18, wherein oneor more cells of the first RAT are configured in a first cell group andone or more cells of the second RAT are configured in a second cellgroup.
 24. A method of wireless communication performed by a userequipment (UE), comprising: identifying one or more symbols, in anuplink subframe designated as uplink by a downlink-referenceuplink-downlink configuration, in which the UE is not permitted totransmit an uplink communication for a first radio access technology(RAT), wherein the UE is in a dual connectivity mode using the first RATand a second RAT; and transmitting an uplink communication for thesecond RAT in the identified one or more symbols.
 25. The method ofclaim 24, wherein the UE is in a single transmission switched uplinkmode, the UE does not have a dynamic power sharing capability, and aprimary cell of the first RAT uses frame structure type
 2. 26. Themethod of claim 24, wherein the one or more symbols are identified basedat least in part on upper layer signaling.
 27. The method of claim 26,wherein the upper layer signaling includes at least one of systeminformation or a radio resource control message.
 28. The method of claim24, wherein the one or more symbols are configured for cell-specificsounding reference signals.
 29. The method of claim 24, wherein one ormore cells of the first RAT are configured in a first cell group and oneor more cells of the second RAT are configured in a second cell group.30. A user equipment (UE) for wireless communication, comprising: amemory; and one or more processors operatively coupled to the memory,the memory and the one or more processors configured to: determinewhether an uplink communication for a first radio access technology(RAT) has been dynamically scheduled or semi-statically configured,wherein the UE is in a dual connectivity mode using the first RAT and asecond RAT; identify an uplink subframe for transmission of the uplinkcommunication based at least in part on whether the uplink communicationhas been dynamically scheduled or semi-statically configured and basedat least in part on a downlink-reference uplink-downlink configuration;and transmit the uplink communication in the identified uplink subframe.